Method for determining binocular performance of a pair of spectacle lenses

ABSTRACT

A method of determining binocular performance of a pair of spectacle lenses comprises: a eyes characteristics providing step, a pair of spectacle lenses providing step, a environment providing step, a cyclopean eye positioning step, a binocular performance criteria defining step, and a binocular performance criteria determining step, wherein the cyclopean eye position is customized.

RELATED APPLICATIONS

This is a U.S. National Phase Application under 35 USC 371 ofInternational Application PCT/EP2010/067777 filed on Nov. 18, 2010.

This application claims the priority of European application no.09306111.7 filed Nov. 18, 2009, the entire content of which is herebyincorporated by reference.

FIELD OF THE INVENTION

The invention relates to a method for determining binocular performanceof a pair of spectacle lenses when a visual environment is seen by theright and left eyes of a wearer through right and left spectacle lensesrespectively.

The invention further relates to a method for optimizing a pair ofspectacle lenses by optimizing the value of at least one binocularcriterion determined according to a determining method according to theinvention.

BACKGROUND OF THE INVENTION

Methods for determining the performance of ophthalmic lenses are wellknown from the person skilled in the art. Such methods are often used inoptimization method to optimize the design of ophthalmic lenses, forexample of progressive ophthalmic lenses.

Most of the methods of the prior art are monocular determinationmethods, wherein the performance of the left and right ophthalmic lensesare evaluated independently one from the other.

Since a person observes its environment with both eyes, the simulationof visual perception with a single eye is not always sufficient for thepurpose of expressing and evaluating the visual perception of anenvironment observed through spectacle glasses.

Document U.S. Pat. No. 6,979,084 discloses a determining method fordetermining binocular performance of a pair of spectacle lenses. Themethod disclosed in U.S. Pat. No. 6,979,084 provides the possibility ofevaluating the binocular performances of a pair of ophthalmic lenses foran average wearer and only for specific criteria such as binocularresidual correction error or binocular vertical deviation. Therefore,the binocular performance determination method disclosed in U.S. Pat.No. 6,979,084 may not always be sufficient for the purpose of expressingand evaluating the visual perception of an environment observed throughspectacle glasses by a given wearer.

SUMMARY OF THE INVENTION

The present invention makes it possible to evaluate the binocular visualperception of a given environment observed through spectacle glasses bya given wearer.

Thereby, one aspect of the invention relates to a method, for exampleimplemented by technical means, for determining binocular performance ofa pair of spectacle lenses when a visual environment is seen, forexample simultaneously, by the right and left eyes of a wearer throughright and left spectacle lenses respectively, comprising:

a eyes characteristics providing step in which eyes characteristics datarepresenting the characteristics of the right and left eyes of thewearer are provided,

a pair of spectacle lenses providing step in which spectacle datarepresenting the pair of spectacle lenses are provided,

a cyclopean eye positioning step in which the cyclopean eye of thewearer is positioned,

a environment providing step in which visual environment datarepresenting a visual environment are provided,

a binocular performance criteria defining step in which at least onebinocular performance criterion which expresses the binocularperformance of the pair of spectacle lenses for viewing an object pointin the visual environment is defined according to the cyclopean eye,

a binocular performance criteria determining step in which the at leastone binocular performance criterion is determined for a plurality ofobject points distributed in the visual environment,

wherein the position of the cyclopean eye is customized according to thewearer.

Advantageously, the method of determining the binocular performances ofa pair of ophthalmic lenses according to the invention may be customizedaccording to the wearer. The inventors have observed that customizingthe position of the cyclopean eye increases the accuracy of theevaluation of the visual perception of the environment observed throughthe pair of ophthalmic lenses by the wearer.

According to further embodiments of the invention, the method accordingto the invention may comprise the following features alone or incombination:

the technical means are calculating means and/or computer means, and/orprocessing means,

the method may further comprise a eye positioning step in which thecenter of rotation of the left and right eyes are positioned relative toeach other;

the visual environment data are customized according to the age of thewearer and/or the posture of the wearer and/or the ethnicity of thewearer and/or the type of environment in which the wearer is to use thespectacle lenses, and/or the prescription of the wearer, and/or theactivities of the wearer, and/or the head/eye coordination of thewearer, and/or the anatomy of the wearer;

the eyes characteristics data comprise measured values of the relativeposition of the left and right eyes of the wearer, and during the eyepositioning step the center of rotation of the left and right eyes arepositioned relative to each other according to the measured values;

the spectacle data comprise mounting data of the spectacle lenses andduring the spectacle lenses positioning step the spectacle lenses arepositioned according to the mounting data;

the spectacle data comprise for the right and left spectacle lenses thevertex distance and/or the pantoscopic angle and/or the wrap angle ofthe spectacle lens, and the method further comprises, prior to thebinocular performance criteria determining step, a spectacle lensespositioning step in which the left and right spectacle lenses arepositioned relative to the center of rotation of the right and left eyesrespectively according to the vertex distance and/or the pantoscopicangle and/or the wrap angle;

in central vision, the binocular performance criteria determining stepcomprise:

a cyclopean gaze direction sampling step in which the visual environmentis sampled based on a cyclopean gaze direction,

a object point determining step in which for each cyclopean gazedirection a corresponding object point of the visual environment isdetermined,

a left eye direction determining step in which for each of the objectpoints determined during the object point determining step the leftdirection of a ray starting from the center of rotation of the left eyeand focusing trough the left spectacle lens to the corresponding objectpoint of the visual environment is determined,

a right eye direction determining step in which for each of the objectpoints determined during the object point determining step the rightdirection of a ray starting from the center of rotation of the right eyeand focusing trough the right spectacle lens to the corresponding objectpoint of the visual environment is determined,

a left eye monocular performance criteria determining step in which foreach of the directions determined during the left eye directiondetermining step at least one left monocular performance criterion forthe left spectacle lens is determined,

a right eye monocular performance criteria determining step in which foreach of the directions determined during the right eye directiondetermining step at least one right monocular performance criterion forthe right spectacle lens is determined,

and wherein at least one binocular criterion is determined according tothe at least one right and left monocular performance criterion;

in peripheral vision the binocular performance criteria determining stepcomprise:

a cyclopean gaze direction determining step in which a cyclopean gazedirection is determined,

a first object point determining step in which for the cyclopean gazedirection a corresponding object point of the visual environment isdetermined,

a left eye direction determining step in which for the object pointdetermined during the first object point determining step the leftdirection of a ray starting from the center of rotation of the left eyeand focusing trough the left spectacle lens to the corresponding objectpoint of the visual environment is determined,

a left pupil positioning step in which the pupil of the left eyecorresponding to the left direction is positioned,

a right eye direction determining step in which for the first objectpoint determined during the object point determining step the rightdirection of a ray starting from the center of rotation of the right eyeand focusing trough the right spectacle lens to the corresponding objectpoint of the visual environment is determined,

a right pupil positioning step in which the pupil of the right eyecorresponding to the right direction is positioned,

a cyclopean gaze direction sampling step in which the visual environmentis sampled based on a cyclopean gaze direction,

a second object point determining step in which for each cyclopean gazedirection a corresponding object point of the visual environment isdetermined,

a left pupil direction determining step in which for each of the objectpoints determined during the second object point determining step theleft direction of a ray starting from the pupil of the left eye andfocusing trough the left spectacle lens to the corresponding objectpoint of the visual environment is determined,

a right pupil direction determining step in which for each of the objectpoints determined during the second object point determining step theright direction of a ray starting from the pupil of the right eye andfocusing trough the right spectacle lens to the corresponding objectpoint of the visual environment is determined,

a left eye monocular performance criteria determining step in which foreach of the directions determined during the left pupil directiondetermining step at least one left monocular performance criterion forthe left spectacle lens is determined,

a right eye monocular performance criteria determining step in which foreach of the directions determined during the right pupil directiondetermining step at least one right monocular performance criterion forthe right spectacle lens is determined,

and wherein at least one binocular criterion is determined according tothe at least one right and left monocular performance criterion; and

the at least one binocular criterion is selected among one or acombination of the following criteria groups consisting of:

-   -   central vision criteria group consisting of:

total prismatic deviation in central vision,

horizontal ocular deviation in central vision,

total ocular deviation in central vision,

variation of any of the preceding central vision criteria,

-   -   peripheral vision criteria group consisting of:

power in peripheral vision,

astigmatism in peripheral vision,

horizontal prismatic deviation in peripheral vision,

vertical prismatic deviation in peripheral vision,

total prismatic deviation in peripheral vision,

total pupil field ray deviation,

vertical pupil field ray deviation,

horizontal pupil field ray deviation,

magnification in peripheral vision,

variation of any of the preceding peripheral vision criteria,

added horizontal disparity,

total horizontal disparity,

added vertical disparity,

total vertical disparity,

rotation binocular cyclodisparity,

fusional horizontal translation, or

fusional vertical translation.

Another aspect of the invention relates to an optimizing method, forexample implemented by technical means, for optimizing at least a lensof a pair of spectacle lenses by optimizing the value of at least onebinocular criterion determined according to the invention. According toan embodiment of the invention, the right or left lens of a pair ofspectacle lenses can be optimized as follows: the optimization methodmay comprise minimizing a cost function, for example the cost functionmay be of the type of the Least squares.

For example the cost function may be:

${CF} = {\sum\limits_{i}{\sum\limits_{k}^{n}{\alpha_{ki}\left( {V_{ki} - {VC}_{ki}} \right)}^{2}}}$

With n the total number of criteria considered, i the cyclopean gazedirection, α_(ki) the weight of each criteria, Vc_(ki) the target valueof the k-th criteria in the cyclopean gaze direction i, V_(ki) the valueof the k-th criteria in the cyclopean gaze direction i. The costfunction may comprise binocular criteria and monocular criteria of thelens to be optimized.

For example, one may choose a binocular and monocular criterion toensure achievement of the prescribed power. For example, one may seek tominimize horizontal disparities added while maintaining the prescribedpower of the lens to be optimized.

According to an embodiment of the invention, the technical means arecalculating means and/or processing means and/or computer means.According to an embodiment of the invention, the technical means are thesame as the one used to implement the method for determining thebinocular criterion.

The optimizing method may further comprise:

-   -   a lenses providing step, in which a pair of spectacle lenses is        provided,    -   an analyzing step, in which the binocular performance of the        pair of spectacle lenses is analyzed according to a method        according to the invention,    -   an modifying step, in which an modifying step, in which at least        one of the two lens of the pair of spectacle lenses is modified,        wherein the analyzing and modifying steps are implemented by        technical means and repeated so as to optimize the binocular        performance of the pair of spectacle lenses.

The invention further relates to a method for manufacturing a pair ofspectacle lenses comprising successively:

-   -   an optimizing step, in which the pair of spectacle lenses is        optimized using a method according to the invention and    -   a manufacturing step, in which the pair of spectacle lenses is        manufactured.

Another aspect of the invention relates to a computer program productcomprising one or more stored sequence of instruction that is accessibleto a processor and which, when executed by the processor, causes theprocessor to carry out the steps of a method according to the invention.

Another aspect of the invention relates to a computer readable mediumcarrying one or more sequences of instructions of the computer programproduct of the invention.

Unless specifically stated otherwise, as apparent from the followingdiscussions, it is appreciated that throughout the specificationdiscussions utilizing terms such as “computing”, “calculating”,“generating”, or the like, refer to the action and/or processes of acomputer or computing system, or similar electronic computing device,that manipulate and/or transform data represented as physical, such aselectronic, quantities within the computing system's registers and/ormemories into other data similarly represented as physical quantitieswithin the computing system's memories, registers or other suchinformation storage, transmission or display devices. Embodiments of thepresent invention may include apparatuses for performing the operationsherein. This apparatus may be specially constructed for the desiredpurposes, or it may comprise a general purpose computer or DigitalSignal Processor (“DSP”) selectively activated or reconfigured by acomputer program stored in the computer or Very high speed integratedcircuit Hardware Description Language (“VHDL”), or Complex InstructionSet Computer (“CISC”) architecture, for example X 86, or ReducedInstruction Set Computer (“RISC”) architecture, for example ARM.

Such a computer program may be stored in a computer readable storagemedium, such as, but is not limited to, any type of disk includingfloppy disks, optical disks, CD-ROMs, magnetic-optical disks, read-onlymemories (ROMs), random access memories (RAMs) electrically programmableread-only memories (EPROMs), electrically erasable and programmable readonly memories (EEPROMs), magnetic or optical cards, or any other type ofmedia suitable for storing electronic instructions, and capable of beingcoupled to a computer system bus.

The processes and displays presented herein are not inherently relatedto any particular computer or other apparatus. Various general purposesystems may be used with programs in accordance with the teachingsherein, or it may prove convenient to construct a more specializedapparatus to perform the desired method. The desired structure for avariety of these systems will appear from the description below. Inaddition, embodiments of the present invention are not described withreference to any particular programming language. It will be appreciatedthat a variety of programming languages may be used to implement theteachings of the inventions as described herein.

In the scope of the present invention, the aforementioned terms areunderstood according to the following definitions:

-   -   The vertex distance is the distance between the back surface of        the lens and the apex of the cornea, measured usually along the        visual axis of the eye in the primary position, usually taken to        be the horizontal.    -   The pantoscopic angle is the angle in the vertical plane between        the optical axis of the spectacle lens and the visual axis of        the eye in the primary position, usually taken to be the        horizontal.    -   The wrap angle is the angle in the horizontal plane between the        optical axis of the spectacle lens and the visual axis of the        eye in the primary position, usually taken to be the horizontal.    -   Each lens of a pair of spectacle lenses is defined by the        modelling of all its surfaces, the refractive index of the        glasses and the position of each surface relatively to each        other (offset, rotation and tilt). These elements are referred        as the parameters of the optical system. Surfaces of an optical        system are usually represented according to a polynomial or        parametric equation obtained by using a model based on the        B-splines or Zernike polynomials. These models give continuous        curvature on the whole lens. Surfaces can also be Fresnel or        pixelized surfaces. The refractive index of materials can be        inhomogeneous and depend on some parameters of the optical        system.    -   Central vision (also referred as foveal vision) describes the        work of the fovea, a small area in the center of the retina that        contains a rich collection of cones. In a central vision        situation, an observer looks at an object which stays in a gaze        direction and the fovea of the observer is moved to follow the        object. Central vision permits a person to read, drive, and        perform other activities that require fine and sharp vision.    -   A gaze direction is defined by two angles measured with regard        to a direct orthonormal basis centered on the center of rotation        of the right or left eye.    -   A cyclopean gaze direction is defined by two angles measured        with regard to a direct orthonormal basis centered on the center        of rotation of the cyclopean eye.    -   Peripheral vision describes the ability to see objects and        movement outside of the direct line of vision. In a peripheral        vision situation, an observer looks in a fixed gaze direction        and an object is seen out of this direct line of vision. The        direction of a ray coming from the object to the eye is then        different from the gaze direction and is referred as peripheral        ray direction.    -   A peripheral ray direction is defined by two angles measured        with regard to a direct orthonormal basis centered on the eye        entrance pupil and moving along the gaze direction axis for the        right or left eyes.    -   Variation of a central vision criterion evaluated thanks to an        evaluation function in a particular gaze direction (α₁, β₁)        according to a component of the gaze direction is understood as        the derivative of the said evaluation function of the said        criterion with respect to the said component. Considering a        evaluation function H_(k), one can consider the partial        derivative of H_(k) with respect to

$\alpha\text{:}\mspace{14mu}\frac{\partial H_{k}}{\partial\alpha}{\left( {\alpha_{1},\beta_{1}} \right).}$One can consider the partial derivative of H_(k) with respect to

$\beta\text{:}\mspace{14mu}\frac{\partial H_{k}}{\partial\beta}{\left( {\alpha_{1},\beta_{1}} \right).}$Variation of a criteria can be evaluated as the composition of thepartial derivatives of the evaluation function with respect to α and/orto β, as for example:

${\frac{\partial H_{k}}{\partial\alpha}\left( {\alpha_{1},\beta_{1}} \right)},{or},{\frac{\partial H_{k}}{\partial\beta}\left( {\alpha_{1},\beta_{1}} \right)},{{or}\mspace{14mu}\sqrt{\left( {\frac{\partial H_{k}}{\partial\alpha}\left( {\alpha_{1},\beta_{1}} \right)} \right)^{2} + \left( {\frac{\partial H_{k}}{\partial\beta}\left( {\alpha_{1},\beta_{1}} \right)} \right)^{2}}}$

-   -   Magnification in peripheral vision is defined as the ratio        between the apparent angular size (or the solid angle) of an        object seen in peripheral vision without lens and the apparent        angular size (or the solid angle) of an object seen through the        lens in peripheral vision.

Magnification in central vision is defined as the ratio between theapparent angular size (or the solid angle) of an object seen in centralvision without lens and the apparent angular size (or the solid angle)of an object seen through the lens in central vision.

-   -   Variation of a peripheral vision criterion evaluated thanks to        an evaluation function in a particular ray direction (α′₁, β′₁)        according to a component of the ray direction is understood as        the derivative of the said evaluation function of the said        criterion with respect to the said component. Considering a        evaluation function H_(k), one can consider the partial        derivative of H_(k) with respect to

$\alpha^{\prime}\text{:}\mspace{14mu}\frac{\partial H_{k}}{\partial\alpha^{\prime}}{\left( {\alpha_{1}^{\prime},\beta_{1}^{\prime}} \right).}$One can consider the partial derivative of H_(k) with respect to

$\beta^{\prime}\text{:}\mspace{14mu}\frac{\partial H_{k}}{\partial\beta^{\prime}}{\left( {\alpha_{1}^{\prime},\beta_{1}^{\prime}} \right).}$Variation of a criteria can be evaluated as the composition of thepartial derivatives of the evaluation function with respect to α′ and toβ′, as for example:

${\frac{\partial H_{k}}{\partial\alpha^{\prime}}\left( {\alpha_{1}^{\prime},\beta_{1}^{\prime}} \right)\mspace{14mu}{or}\mspace{14mu}\frac{\partial H_{k}}{\partial\beta^{\prime}}\left( {\alpha_{1}^{\prime},\beta_{1}^{\prime}} \right)},{{or}\mspace{14mu}{\sqrt{\left( {\frac{\partial H_{k}}{\partial\alpha^{\prime}}\left( {\alpha_{1}^{\prime},\beta_{1}^{\prime}} \right)} \right)^{2} + \left( {\frac{\partial H_{k}}{\partial\beta^{\prime}}\left( {\alpha_{1}^{\prime},\beta_{1}^{\prime}} \right)} \right)^{2}}.}}$

-   -   The posture of the wearer may be defined by posture parameters        well known from the person skilled in the art. W02007/068818 and        WO 2007/068819 illustrate such posture parameters.    -   The visual environment may be defined by the distances of object        points as a function of the gaze directions. For example, the        visual environment may be defined as the distances between the        object points and the cyclopean eye as a function of the        cyclopean gaze directions.    -   The activities of the wearer may be understood as the visual        habits of the wearer. The activities of the wearer may be chosen        among the following examples: near vision activities such as        reading or writing, close vision activities such as sewing or        modeling, far vision activities such as shooting, intermediate        vision activities such as computer, or other types of activities        such as frequent driving, intensive reading, or high movement        activities such as sport.    -   The head/eye coordination of the wearer corresponds to the        ability of a wearer to have the movement of his eyes and his        head coordinate when looking trough a visual environment    -   Power in peripheral vision is defined as the power generated by        the optical system when the wearer observes an object in        peripheral vision;    -   astigmatism in peripheral vision is defined as the astigmatism        generated by the optical system both as regards amplitude and        the axis when the wearer observes an object in peripheral        vision;    -   total prismatic deviation in central vision is defined in the        object space by the angular deviation of a ray issued from the        center of rotation of the eye introduced by the quantity of        prism of the lens;    -   horizontal prismatic deviation in central vision is defined in        the object space by the angular deviation in an horizontal plan        of a ray issued from the center of rotation of the eye        introduced by the quantity of prism of the lens;    -   vertical prismatic deviation in central vision is defined in the        object space by the angular deviation in an vertical plan of a        ray issued from the center of rotation of the eye introduced by        the quantity of prism of the lens;    -   total prismatic deviation in peripheral vision is the angular        deviation of a ray issued from the center of the entrance pupil        introduced by the quantity of prism of the lens;    -   horizontal prismatic deviation in peripheral vision is the        angular deviation in an horizontal plan of a ray issued from the        center of the entrance pupil introduced by the quantity of prism        of the lens;    -   vertical prismatic deviation in peripheral vision is the angular        deviation in an vertical plan of a ray issued from the center of        the entrance pupil introduced by the quantity of prism of the        lens;    -   total ocular deviation is defined in central vision and        describes the fact that adding a lens causes an eye to rotate in        order to stay focused on the same object. The angle can be        measured in prismatic diopters;    -   horizontal ocular deviation corresponds to the horizontal        component of the total ocular deviation;    -   the deformation of a series of points is obtained by a system of        ray tracing that provides the localisation of different        components of the visual environment, seen by the wearer trough        the pair of spectacle lenses in peripheral vision independently        of the area of the spectacle lenses used in central vision, the        system consist in calculating the image of each point of the        series of points trough the pair of spectacle lenses, examples        of definition of deformations are given in “Points de vue” n°        42—Printemps 2000—Varilux Panamic, la demarche de conception and        in “Vision research”, vol. 35 supplement, October 1995, p        S245—Distorsion induced by ophthalmic lenses—Simonet P.,        Bourdoncle B., Miège C., Gresset J., Faubert J,    -   the disparities may be determined by defining:        -   a cyclopean gaze fixation direction between the cyclopean            eye and a fixation point F of the visual environment,        -   a first plan P1 comprising the centers of rotation of the            right and left eyes and the fixation point F of the visual            environment,        -   a second plan P2 orthogonal to the line joining the centers            of rotation of the right and left eyes and comprising the            fixation point F of the visual environment,        -   a calculation plan P3 orthogonal to the first and second            plans and situated at a given distance of the cyclopean eye,        -   to define the total disparity, the visual environment is            sampled into a plurality of cyclopean gaze directions; a            series of points corresponding to the intersections of each            cyclopean gaze direction with the calculation plan P3 is            defined,        -   a deformation of the series of points comprised in the            calculation plan P3 is determined trough the right and left            lens, each eyes staring at the fixation point F,        -   this determination gives for each eye, and in relation to            its visual axis, the angular position of all the points of            the deformation of the series of points,        -   the fixation disparity is canceled, if necessary by            subtracting to all the positions the position of the            fixation point F,        -   each point of the point of the series of points is deformed            into a left deformation point and right deformed point,            called conjugated,        -   the total disparity is defined as the difference in angular            position of the conjugated points,        -   the total horizontal disparity is defined as the difference            in angular position of the conjugated points in the first            plan P1,        -   the total vertical disparity is defined as the difference in            angular position of the conjugated points in the second plan            P2, the natural disparity is defined as the total disparity            when the wearer is looking directly at the fixation point F            of the visual environment, without the spectacle lenses,        -   the added disparity corresponds to the difference between            the total and the natural disparities,        -   the added horizontal disparity corresponds to the difference            between the total horizontal and the natural horizontal            disparities,        -   the added vertical disparity corresponds to the difference            between the total vertical and the natural vertical            disparities.    -   The cyclodisparities may be determined further to the        disparities by first defining:        -   a first axis A1 comprised in the calculation plan P3 and            colinear to the line joining the centers of rotation of the            right and left eyes,        -   a second axis A2 comprised in the calculation plan P3 and            perpendicular to the first axis A1,    -   and by:        -   selecting a analytic cone having its axis corresponding to            the cyclopean gaze fixation direction and having a total            angle comprised between 0° and 180°,        -   calculating the deformation of the series of points for the            right an left eyes (as for the disparities),        -   applying to the two deformed series of points a translation            movement along the first axis A1, the second axis A2 and a            rotation around the visual axis of the right and left eye so            as to minimize the position differences on the analytic cone            (vertical, or horizontal or both) between the conjugated            points of the two deformed series of points, this may be            done by minimizing their RMS in the analytic cone:    -   the amount of translation between the two deformed series of        points along the first axis A1 corresponds to the fusional        horizontal translation,    -   the amount of translation between the two deformed series of        points along the second axis A2 corresponds to the fusional        vertical translation,    -   the amount of rotation between the two deformed series of points        around the visual axis of the right and left eye corresponds to        the rotation binocular cyclodisparity.

BRIEF DESCRIPTION OF THE DRAWINGS

Non limiting embodiments of the invention will now be described withreference to the following drawings, wherein:

FIG. 1 a flowchart of the steps of an embodiment of the method accordingto the invention.

FIG. 2 shows a eyes-lenses system according to an embodiment of theinvention.

FIG. 3 shows a ray tracing from the center of rotation of an eye.

FIG. 4 shows a ray tracing from the center of the eye entrance pupil.

FIG. 5 illustrates prismatic deviation in peripheral vision.

FIG. 6 illustrates ocular deviation.

FIG. 7 illustrates pupil ray field deviation.

FIG. 8 illustrates horizontal prismatic deviation in central vision.

FIG. 9 illustrates postural parameters,

FIGS. 10 a and 10 b illustrate the contour plot of the difference inpower between the right and left spectacle lenses determined using amethod of the invention.

Skilled artisans can appreciate that elements in the figures areillustrated for simplicity and clarity and have not necessarily beendrawn to scale. For example, the dimensions of some of the elements inthe figures may be exaggerated relative to other elements to helpimprove the understanding of the embodiments of the present invention.

DETAILED DESCRIPTION

According to an embodiment of the invention illustrated on FIG. 1, themethod of determining binocular performance of a pair of spectaclelenses comprises:

a eyes characteristics providing step S1,

a pair of spectacle lenses providing step S2,

a environment providing step S3,

a cyclopean eye positioning step S4,

a binocular performance criteria defining step S5, and

a binocular performance criteria determining step S6.

During the eyes characteristics providing step S1, eyes characteristicsdata ECD representing the characteristics of the right and left eyes ofthe wearer are provided.

The eyes characteristics data ECD may comprise measured values, forexample inter-pupil distance or pupil height, or the relative positionof the left and right eyes of the wearer or the position of the centerof rotation of the left and right eyes of the wearer. Advantageously,having measured values increases the accuracy of the overall method.

The eyes characteristics data ECD may comprise average values based onknown average values of the relative position of the left and right eyesof the wearer.

During the pair of spectacle lenses providing step S2, spectacle data SPrepresenting the pair of spectacle lenses are provided.

According to an embodiment of the invention, the spectacle data SPcomprise mounting data of the spectacle lenses.

According to an embodiment of the invention, the spectacle data comprisefor the right and left spectacle lenses the vertex distance and/or thepantoscopic angle and/or the wrap angle of the spectacle lens.

During the environment providing step S3, visual environment data VEDare provided. The visual environment data VED represent a visualenvironment that the wearer could see trough the spectacle lenses.

According to an embodiment of the invention, the visual environment mayvary according to the wearers activities. For example in lower cyclopeangaze direction, the distance between the cyclopean eye and the objectpoint is smaller for a computer user (attaching a keyboard) than for atrekker (soil fixation).

According to an embodiment of the invention, the visual environment mayvary according to the wearers anatomy. For example in lower cyclopeangaze direction, the distance between the cyclopean eye and the objectpoint is smaller for a small person than for a tall person.

According to an embodiment of the invention, the visual environment mayvary according to the wearers age. For example in lower cyclopean gazedirection, the distance between the cyclopean eye and the object pointis smaller for a child than for an adult.

According to an embodiment of the invention, the visual environment mayvary according to the wearer's posture. For example to look at acomputer the distance between the cyclopean eye and the object point isdifferent for a wearer who stands upright or bent.

According to an embodiment of the invention, the visual environment mayvary according to the wearers ethnicity. For example in lower cyclopeangaze direction, the distance between the cyclopean eye and the objectpoint is smaller for an Asian wearer than for a Caucasian wearer.

The visual environment may be individually customized for a given wearerby measuring for each cyclopean gaze direction of a visual space of agiven wearer the distance between the object point and the cyclopeaneye.

According to an embodiment of the invention, typical visual environmentsmay be defined. For example, for each member of a group of given wearers(eg group of wearers of 10 years old, or group of wearers of 20 yearsold) an individually customized environment is measured, and the typicalenvironment is determined as a combination of the individuallycustomized environments of the members of a same group (eg the average).

According to an embodiment of the invention, to overcome the tediousprocess of measuring the wearer's individually customized visualenvironment, the visual environment may be adapted to a given wearerwithout going trough the process of individual measurements. For examplethe skilled person may build a database of typical environments and thenset the visual environment best suited to the wearer. For example for a15 years old wearer the visual environment may be determined byinterpolation of the typical visual environment corresponding to 10years old wearers and the typical visual environment corresponding to 20years old wearers.

According to another example of the invention, for a 11 years old wearerthe visual environment may be chosen as the typical visual environmentof 10 years old wearers.

According to an embodiment of the invention, the visual environment dataVED are customized according to the age of the wearer and/or the postureof the wearer and/or the ethnicity of the wearer and/or the type ofenvironment in which the wearer is to use the spectacle lenses, and/orthe prescription of the wearer, and/or the activities of the wearer,and/or the head/eye coordination of the wearer, and/or the anatomy ofthe wearer.

During the cyclopean eye positioning step S4, the cyclopean eye CE ofthe wearer is positioned. The position of the cyclopean eye CE iscustomized.

According to an embodiment of the invention, the cyclopean eye CE may bepositioned according to a measured position. The person skilled in theart may use any known measuring method to determine the position of thecyclopean eye CE.

According to an embodiment of the invention, the position of thecyclopean eye CE is determined using the measured dominance between theright and left eyes.

For example, the cyclopean eye CE may be positioned on the line betweenthe centers of rotation of the right and left eyes. The position of thecyclopean eye on said line may be determined by the following equation:

$\overset{\rightarrow}{{CRRE} \cdot {CE}} = {\frac{1 + e}{2}*\left( \overset{\rightarrow}{{CRRE} \cdot {CRLE}} \right)}$with e the dominance rate of the wearer, {right arrow over (CRRE·CE)},the vector between the center of rotation of the right eye and thecenter of rotation of the cyclopean eye, and ({right arrow over(CRRE·CRLE)}) the vector between the center of rotation of the left eyeand the center of rotation of the cyclopean eye.

For example, when e=−1 the cyclopean eye is the right eye, when e=1 thecyclopean eye is the left eye, and when −1<e<1 the cyclopean eye isbetween the right and left eye.

According to an embodiment of the invention, the method may comprise aneyes-lenses system determining step in which an eyes-lenses system isdetermined.

The eyes-lenses system determining step may comprises a eye positioningstep in which the center of rotation of the left and right eyes arepositioned relative to each other, a spectacle lenses positioning stepin which the left and right spectacle lenses are positioned relative tothe center of rotation of the right and left eyes respectively.

According to an embodiment of the invention, the spectacles lenses maybe positioned according to the vertex distance and/or the pantoscopicangle and/or the wrap angle.

FIG. 2 illustrates a schematic view of a eyes-lenses system.

Referring to FIG. 2, the right eye position can be defined by the centerof rotation of the right eye CRRE and the right entrance pupil centralpoint RP. RPS is the right pupil size (not drawn to scale). The distanceRq′ between the CRRE and the right lens 20 is generally, but not limitedto, set to 25.5 mm, and Rp′ defines the position of the right eyeentrance pupil with respect to the center of rotation of the right eyeCRRE.

Further referring to FIG. 2, the left eye position can be defined by thecenter of rotation of the left eye CRLE and the left entrance pupilcentral point LP. LPS is the left pupil size (not drawn to scale). Thedistance Lq′ between the CRLE and the left lens 21 is generally, but notlimited to, set to 25.5 mm, and Lp′ defines the position of the left eyeentrance pupil with respect to the center of rotation of the left eyeCRLE.

According to an embodiment of the invention, the distances Rq′ and Lq′are determined according to the spectacle data and eye characteristicdata.

According to an embodiment of the invention, during the eye positioningstep the center of rotation of the left and right eyes are positionedrelative to each other according to the measured values.

According to an embodiment of the invention, the cyclopean eye positingstep S4 is implemented further to the eyes-lenses system determiningstep. The cyclopean eye of the wearer is positioned in the eyes-lensessystem.

According to an embodiment of the invention, further to the cyclopeaneye positing step S4, the method comprises an environment positioningstep, in which an environment corresponding to the visual environmentdata VED provided during the environment providing step S3, ispositioned before the eyes-lenses system.

Further to the environment positioning step, the method according to theinvention comprises a binocular performance criteria defining step S5.During the binocular performance criteria defining step S5, at least onebinocular performance criterion BPC which expresses the binocularperformance of the pair of spectacle lenses for viewing an object pointin the visual environment is defined according to the cyclopean eye.

According to an embodiment of the invention, the binocular performancecriterion BPC is selected among one or a combination of the followingcentral vision criteria:

horizontal prismatic deviation in central vision,

vertical prismatic deviation in central vision,

total prismatic deviation in central vision,

magnification in central vision,

horizontal ocular deviation in central vision,

total ocular deviation in central vision, and

variation of any of the preceding central vision criteria.

According to an embodiment of the invention, the binocular performancecriterion BPC is selected among one or a combination of the followingcentral vision criteria:

horizontal prismatic deviation in central vision,

total prismatic deviation in central vision,

magnification in central vision,

horizontal ocular deviation in central vision,

total ocular deviation in central vision, and

variation of any of the preceding central vision criteria.

According to an embodiment of the invention, the binocular performancecriterion BPC is selected among one or a combination of the followingcentral vision criteria:

horizontal prismatic deviation in central vision,

vertical prismatic deviation in central vision,

total prismatic deviation in central vision,

horizontal ocular deviation in central vision,

total ocular deviation in central vision,

variation of any of the preceding central vision criteria.

According to an embodiment of the invention, the binocular performancecriterion BPC is selected among one or a combination of the followingcentral vision criteria:

horizontal prismatic deviation in central vision,

total prismatic deviation in central vision,

horizontal ocular deviation in central vision,

total ocular deviation in central vision, and

variation of any of the preceding central vision criteria.

According to an embodiment of the invention, the binocular performancecriterion BPC is selected among one or a combination of the followingcentral vision criteria:

horizontal ocular deviation in central vision,

total ocular deviation in central vision, and

variation of any of the preceding central vision criteria.

According to an embodiment of the invention, the binocular performancecriterion BPC is selected among one or a combination of the followingcentral vision criteria:

total prismatic deviation in central vision,

horizontal ocular deviation in central vision,

total ocular deviation in central vision, and

variation of any of the preceding central vision criteria.

According to an embodiment of the invention, the binocular performancecriterion BPC is total ocular deviation in central vision.

According to an embodiment of the invention, the binocular performancecriterion BPC is selected among one or a combination of the followingcentral vision criteria:

total prismatic deviation in central vision,

total ocular deviation in central vision, and

variation of any of the preceding central vision criteria.

According to an embodiment of the invention, the binocular performancecriterion BPC is selected among one or a combination of the followingperipheral vision criteria:

power in peripheral vision,

astigmatism in peripheral vision,

horizontal prismatic deviation in peripheral vision,

vertical prismatic deviation in peripheral vision,

total prismatic deviation in peripheral vision,

total pupil field ray deviation,

vertical pupil field ray deviation,

horizontal pupil field ray deviation,

magnification in peripheral vision, and

variation of any of the preceding peripheral vision criteria.

According to an embodiment of the invention, the binocular performancecriterion BPC is selected among one or a combination of the followingperipheral disparity vision criteria:

added horizontal disparity,

total horizontal disparity,

added vertical disparity, and

total vertical disparity.

According to an embodiment of the invention, the binocular performancecriterion BPC is selected among one or a combination of the followingperipheral cyclodisparity vision criteria:

rotation binocular cyclodisparity,

fusional horizontal translation, and

fusional vertical translation.

Further to the binocular performance criteria defining step S5, themethod according to the invention comprises a binocular performancecriteria determining step S6.

In order to compute a criterion, ray tracing method can be used. Raytracing has special features according to the model of the eyes-lensessystem.

FIG. 3 illustrates a model for central vision in the purpose ofassessing a criterion in a central vision situation by ray tracing. In acentral vision situation, the eye rotates about its center of rotationas well as the entrance pupil of the eye. The visual environment issampled based on a cyclopean gaze direction. A gaze direction is definedby two angles (α,β) measured with regard to reference axes R=(X,Y,Z)centered on the cyclopean eye of the wearer CE.

For each cyclopean gaze direction (α,β) a corresponding object point OPof the visual environment is determined. For example a gaze ray 1 isbuilt from the cyclopean eye in the gaze direction (α,β).

A left direction (α_(L),β_(L)) of a ray 11L starting from the center ofrotation of the left eye CRLE and focusing trough the left spectaclelens 21 to the object point OP of the visual environment VE isdetermined.

A right direction (α_(R),β_(R)) of a ray 11R starting from the center ofrotation of the right eye CRRE and focusing trough the right spectaclelens 20 to the object point OP of the visual environment VE isdetermined.

According to an embodiment of the invention, a left monocularperformance criterion for the left spectacle lens 21 is determined inthe left direction (α_(L),β_(L)) and a right monocular performancecriterion for the right spectacle lens 20 is determined in the rightdirection (α_(R),β_(R).

The binocular criterion is determined for each cyclopean gaze direction(α,β) according to the right and left monocular performance criterion inthe right direction (α_(R),β_(R)) and left direction (α_(L),β_(L)).

FIG. 4 illustrates a model for peripheral vision in the purpose ofassessing a criterion in a peripheral vision situation through raytracing.

According to an embodiment of the invention, the method to determine thebinocular performance of a pair of spectacles lenses in the peripheralvision corresponds to the method for central vision with the provisothat the right (α_(R),β_(R)) and left (α_(L),β_(L)) directions startfrom the right and left pupil and not the center of rotation of theright and left eyes.

As for central vision criteria, the visual environment is sampled basedon a cyclopean gaze direction. A gaze direction is defined by two angles(α,β) (not represented) measured with regard to reference axes R=(X,Y,Z)centered on the cyclopean eye of the wearer CE.

For each cyclopean gaze direction (α,β) a corresponding object point OPof the visual environment is determined.

For the right and left eyes, the monocular performance criteria areevaluated as illustrated on FIG. 4. A gaze direction (α,β) (notrepresented here) is fixed, and an object of the visual environment VEis viewed in a peripheral ray direction different from the gazedirection. A peripheral ray direction is defined by two angles (α′,β′)measured with regard to reference axes R′=(X′,Y′,Z′) centered on the eyeentrance pupil and moving along the gaze direction axis given by thefixed direction (α,β) and represented by axis X′ on FIG. 4. Forassessing a monocular peripheral vision criterion in a peripheral raydirection (α′,β′), a peripheral ray 2 is built from the center of thepupil P in a peripheral ray direction (α′,β′). 22 is the incident rayafter passing through the lens 20.

As for central vision criteria the binocular criterion is determined foreach cyclopean gaze direction (α,β) according to the right and leftmonocular performance criterion in the right direction (α_(R),β_(R)) andleft direction (α_(L),β_(L)).

According to an embodiment of the invention, the binocular performancecriterion in central and/or peripheral vision is determined using alinear or a substantially linear combination of the right and leftmonocular performance criteria, for example a difference.

In the sense of the invention a substantially linear combination may bedefined as a combination of linear element and non-linear element,wherein the non-linear element has a value small compared to the linearelements, for example at least 10 time smaller.

According to an embodiment of the invention, a binocular criteria may bedefined as: Mono A−Mono B+ε, with Mono A and Mono B a first and secondmonocular criteria and ε a non-linear function of Mono A and Mono Bwhose absolute value is small compared to Mono A and Mono B. For example

$ɛ = \frac{({MonoA})*({MonoB})}{10^{N}}$with N a integer greater or equal to 1.

According to an embodiment of the invention, the binocular criteria maybe defined as a non linear combination of monocular criteria, forexample:

Min (Mono A, Mono B), or

Max (Mono A, Mono B), or

Root mean square (Mono A, Mono B).

According to an embodiment of the invention, the binocular performancecriterion in central and/or peripheral vision is the average value ofthe right and left monocular criteria.

FIGS. 5 to 9 illustrate criterion evaluation methods according to thepresent invention.

FIG. 5 illustrates ray tracing for estimating prismatic deviation PD inperipheral vision. Prismatic deviation in peripheral vision is estimatedthrough ray tracing of a peripheral ray associated to a peripheral raydirection (α′,β′) given with regard to reference axes centered on thecenter of the entrance pupil and moving along the gaze direction, asdiscussed hereinabove. A ray 2 issued from the center of the entrancepupil in peripheral ray direction (α′,β′) with the gaze direction axisis traced. Incident ray 22 corresponding to ray 2 is then built.Prismatic deviation represents the angle between incident ray 22 and avirtual ray 3 issued from the center of the pupil in the direction ofray 2 and not deviated by the prism of lens 20.

FIG. 6 describes ocular deviation OCD. It shows a first ray 33 comingfrom an object 10 when no lens is placed in its path to the CRE, and asecond ray 120 coming from the same object whose path is modified by theaddition of a lens 20. Ray 12 corresponds to ray 120 in the image spaceafter passing through the lens 20. The ocular deviation OCD in adirection (α,β) is estimated in central vision and is defined as theangle between:

the direction of the eye targeting an object without lens (representedby ray 33) and

the direction of the eye targeting the same object when said lens isplaced in front of the viewer eyes (represented by ray 12).

FIG. 7 illustrates total pupil ray field deviation PRFD, it shows afirst ray 34 coming from an object 10 located in the peripheral field ofview when no lens is placed in its path to the eye entrance pupil, and asecond incident ray 230 coming from the same object whose path ismodified by the introduction of a lens 20. Ray 23 corresponds in theimage field to incident ray 230.

Total pupil field ray deviation PRFD is estimated in peripheral visionand is defined as the angle, measured in the image space, between

-   -   a straight ray 34 coming from an object localised in the        peripheral field of view of an eye and entering the center of        the pupil, and    -   a ray 23 coming from the same object and entering the center of        the pupil when said lens is placed on the eyes of the wearer.

Horizontal pupil field ray deviation corresponds to the horizontalcomponent of the total pupil field ray deviation PRFD.

Vertical pupil field ray deviation corresponds to the vertical componentof the total pupil field ray deviation PRFD.

FIG. 8 illustrates horizontal prismatic deviation HPD in central vision.Prismatic deviation is defined as the angular difference between ray 130and ray 35 in a same horizontal plan. Ray 130 is the image of the ray 13in the object space. Ray 13 is issued from the eye rotation centeraccording to direction (α,β) in the fixed reference axes (X,Y,Z)centered on the eye rotation center as represented on FIG. 8. Ray 35 isa virtual ray issued from the eye rotation center according to direction(α,β) and not deviated by the prism of the lens. Horizontal prismaticdeviation HPD is the component of the prismatic deviation in the plane(XOZ) and can be calculated through:

${{HPD} = \left( {{Arc}\;\sin\;\left( {\left( \frac{V_{ini}^{h}\bigwedge V_{fin}^{h}}{{V_{ini}^{h}}{V_{fin}^{h}}} \right) \cdot \overset{\rightarrow}{y}} \right)} \right)},$wherein V^(h)=V−{right arrow over (y)}(V·{right arrow over (y)}), andV_(ini) and V_(fin) are direction vectors of alternatively ray 13 and130.

FIG. 9 illustrate examples of postural parameters that may be used tocustomize the visual environment according to the invention. Theparameters illustrated on FIG. 9 are:

-   -   the Francfort plan P_(F) that indicates the vertical inclination        of the heads of the wearer 100,    -   the horizontal plan of reference P_(H),    -   the vertical slope angle T of the head of the wearer, measured        in a vertical plan between the plans P_(H) and P_(F),    -   the gaze direction D_(R) of the wearer 100,    -   the lowering gaze angle R, measured in a vertical plan between        the plan P_(H) and the gaze direction D_(R),    -   the lowering or raising of the eyes angle Y, measured in a        vertical plan between the plans P_(F) and the gaze direction        D_(R),    -   the document slope angle B of document 101 read by the wearer        100, measured in a vertical plan between an horizontal plan and        the plan of document 101,    -   the horopter angle H, measured in a vertical plan between the        plan of document 101 and the gaze direction D_(R);    -   the reading distance in near vision Dvp, measured along the gaze        direction D_(R) between the eyes of the wearer 100 and the part        of the document 101 that is being read by the wearer.

The effect of customizing the position of the cyclopean eye isillustrated on FIGS. 10 a and 10 b.

FIG. 10 a represents the contour plot of the difference in power betweenthe right and left spectacle lens determined using a method of theinvention where the cyclopean eye is centered between the right and lefteyes.

FIG. 10 b represents the contour plot of the difference in power betweenthe same right and left spectacle lenses than for FIG. 10 a, determinedusing a method of the invention where the cyclopean eye is positioned atthe center of rotation of the left eye of the wearer.

It appears when comparing FIGS. 10 a and 10 b that the performance of agiven pair of spectacle lenses is influenced by the position of thecyclopean eye of the wearer and therefore by the dominance of thewearer.

The invention has been described above with the aid of embodimentswithout limitation of the general inventive concept.

The invention claimed is:
 1. A method for determining binocularperformance of a pair of spectacle lenses when a visual environment isseen by the right and left eyes of a wearer through right and leftspectacle lenses respectively, comprising: an eyes characteristicsproviding step in which eyes characteristics data representing thecharacteristics of the right and left eyes of the wearer are provided; apair of spectacle lenses providing step in which spectacle datarepresenting the pair of spectacle lenses are provided; an environmentproviding step in which visual environment data representing a visualenvironment are provided; a cyclopean eye positioning step in which thecyclopean eye of the wearer is positioned; a binocular performancecriteria defining step in which at least one binocular performancecriterion which expresses the binocular performance of the pair ofspectacle lenses for viewing an object point in the visual environmentis defined according to the cyclopean eye; and a binocular performancecriteria determining step in which the at least one binocularperformance criterion is determined for a plurality of object pointsdistributed in the visual environment, wherein the position of thecyclopean eye is customized according to the wearer, and wherein thebinocular performance criteria determining step comprises: a cyclopeangaze direction sampling step in which the visual environment is samplebased on a cyclopean gaze direction, an object point determining step inwhich for each cyclopean gaze direction a corresponding object point ofthe visual environment is determined, a left eye direction determiningstep in which for each of the object points determined during the objectpoint determining step the left direction of a ray starting from thecenter of rotation of the left eye and focusing trough the leftspectacle lens to the corresponding object point of the visualenvironment is determined, a right eye direction determining step inwhich for each of the object points determined during the object pointdetermining step the right direction of a ray starting from the centerof rotation of the right eye and focusing trough the right spectaclelens to the corresponding object point of the visual environment isdetermined, a left eye monocular performance criteria determining stepin which for each of the directions determined during the left eyedirection determining step at least one left monocular performancecriterion for the left spectacle lens is determined, and a right eyemonocular performance criteria determining step in which for each of thedirections determined during the right eye direction determining step atleast one right monocular performance criterion for the right spectaclelens is determined, wherein at least one binocular criterion isdetermined according to the at least one right and left monocularperformance criterion.
 2. The method according to claim 1, wherein themethod further comprises an eye positioning step in which the center ofrotation of the left and right eyes are positioned relative to eachother.
 3. The method according to claim 2, wherein the eyescharacteristics data comprise measured values of the relative positionof the left and right eyes of the wearer, and during the eye positioningstep the center of rotation of the left and right eyes are positionedrelative to each other according to the measured values.
 4. The methodaccording to claim 1, wherein the visual environment data are customizedaccording to the age of the wearer and/or the posture of the wearerand/or the ethnicity of the wearer and/or the type of environment inwhich the wearer is to use the spectacle lenses, and/or the prescriptionof the wearer, and/or the activities of the wearer, and/or the head/eyecoordination of the wearer, and/or the anatomy of the wearer.
 5. Themethod according to claim 1, wherein the spectacle data comprisemounting data of the spectacle lenses and the method further comprises,and prior to the binocular performance criteria determining step, aspectacle lenses positioning step in which the spectacle lenses arepositioned according to the mounting data.
 6. The method according toclaim 1, wherein the spectacle data comprise for the right and leftspectacle lenses the vertex distance and/or the pantoscopic angle and/orthe wrap angle of the spectacle lens, and the method further comprises,prior to the binocular performance criteria determining step, aspectacle lenses positioning step in which the left and right spectaclelenses are positioned relative to the center of rotation of the rightand left eyes respectively according to the vertex distance and/or thepantoscopic angle and/or the wrap angle.
 7. The method according toclaim 1, wherein the at least one binocular criterion is selected amongone or a combination of the following criteria groups consisting of:central vision criteria group consisting of: total prismatic deviationin central vision, horizontal ocular deviation in central vision, totalocular deviation in central vision, peripheral vision criteria groupconsisting of: power in peripheral vision, astigmatism in peripheralvision, horizontal prismatic deviation in peripheral vision, verticalprismatic deviation in peripheral vision, total prismatic deviation inperipheral vision, total pupil field ray deviation, horizontal pupilfield ray deviation, vertical pupil field ray deviation, magnificationin peripheral vision, added horizontal disparity, total horizontaldisparity, added vertical disparity, total vertical disparity, rotationbinocular cyclodisparity, fusional horizontal translation, and fusionalvertical translation.
 8. A method for optimizing at least a lens of apair of spectacle lenses by optimizing the value of at least onebinocular criterion determined according to claim
 1. 9. A method formanufacturing a pair of spectacle lenses comprising successively: anoptimizing step, in which the pair of spectacle lenses is optimizedusing the method according to claim 8, and a manufacturing step, inwhich the pair of spectacle lenses is manufactured.
 10. A method foroptimizing at least a lens of a pair of spectacle lenses by optimizingthe value of at least one binocular criterion determined according toclaim 1, wherein the method comprises: a lenses providing step, in whicha pair of spectacle lenses is provided, an analyzing step, in which thebinocular performance of the pair of spectacle lenses is analyzedaccording to the method according to claim 1, a modifying step, in whichat least one of the two lens is modified, wherein the analyzing andmodifying steps are implemented by technical means and repeated so as tooptimize the binocular performance of the pair of spectacle lenses. 11.A computer program product comprising one or more stored sequence ofinstruction that is accessible to a processor and which, when executedby the processor, causes the processor to carry out the step of claim10.
 12. A computer readable medium carrying one or more sequences ofinstructions of the computer program product of claim
 11. 13. A methodfor determining binocular performance of a pair of spectacle lenses whena visual environment is seen by the right and left eyes of a wearerthrough right and left spectacle lenses respectively, comprising: aneyes characteristics providing step in which eyes characteristics datarepresenting the characteristics of the right and left eyes of thewearer are provided; a pair of spectacle lenses providing step in whichspectacle data representing the pair of spectacle lenses are provided;an environment providing step in which visual environment datarepresenting a visual environment are provided; a cyclopean eyepositioning step in which the cyclopean eye of the wearer is positioned;a binocular performance criteria defining step in which at least onebinocular performance criterion which expresses the binocularperformance of the pair of spectacle lenses for viewing an object pointin the visual environment is defined according to the cyclopean eye; anda binocular performance criteria determining step in which the at leastone binocular performance criterion is determined for a plurality ofobject points distributed in the visual environment, wherein theposition of the cyclopean eye is customized according to the wearer, andwherein the binocular performance criteria determining step comprises: acyclopean gaze direction determining step in which a cyclopean gazedirection is determined, a first object point determining step in whichfor the cyclopean gaze direction a corresponding object point of thevisual environment is determined, a left eye direction determining stepin which for the object point determined during the first object pointdetermining step the left direction of a ray starting from the center ofrotation of the left eye and focusing trough the left spectacle lens tothe corresponding object point of the visual environment is determined,a left pupil positioning step in which the pupil of the left eyecorresponding to the left direction is positioned, a right eye directiondetermining step in which for the first object point determined duringthe object point determining step the right direction of a ray startingfrom the center of rotation of the right eye and focusing trough theright spectacle lens to the corresponding object point of the visualenvironment is determined, a right pupil positioning step in which thepupil of the right eye corresponding to the right direction ispositioned, a cyclopean gaze direction sampling step in which the visualenvironment is sampled based on a cyclopean gaze direction, a secondobject point determining step in which for each cyclopean gaze directiona corresponding object point of the visual environment is determined, aleft pupil direction determining step in which for each of the objectpoints determined during the second object point determining step theleft direction of a ray starting from the pupil of the left eye andfocusing trough the left spectacle lens to the corresponding objectpoint of the visual environment is determined, a right pupil directiondetermining step in which for each of the object points determinedduring the second object point determining step the right direction of aray starting from the pupil of the right eye and focusing trough theright spectacle lens to the corresponding object point of the visualenvironment is determined, a left eye monocular performance criteriadetermining step in which for each of the directions determined duringthe left pupil direction determining step at least one left monocularperformance criterion for the left spectacle lens is determined, and aright eye monocular performance criteria determining step in which foreach of the directions determined during the right pupil directiondetermining step at least one right monocular performance criterion forthe right spectacle lens is determined, wherein at least one binocularcriterion is determined according to the at least one right and leftmonocular performance criterion.
 14. The method according to claim 13,wherein the visual environment data are customized according to the ageof the wearer and/or the posture of the wearer and/or the ethnicity ofthe wearer and/or the type of environment in which the wearer is to usethe spectacle lenses, and/or the prescription of the wearer, and/or theactivities of the wearer, and/or the head/eye coordination of thewearer, and/or the anatomy of the wearer.
 15. The method according toclaim 13, wherein the spectacle data comprise for the right and leftspectacle lenses the vertex distance and/or the pantoscopic angle and/orthe wrap angle of the spectacle lens, and the method further comprises,prior to the binocular performance criteria determining step, aspectacle lenses positioning step in which the left and right spectaclelenses are positioned relative to the center of rotation of the rightand left eyes respectively according to the vertex distance and/or thepantoscopic angle and/or the wrap angle.
 16. A method for optimizing atleast a lens of a pair of spectacle lenses by optimizing the value of atleast one binocular criterion determined according to claim
 13. 17. Amethod for manufacturing a pair of spectacle lenses comprisingsuccessively: an optimizing step, in which the pair of spectacle lensesis optimized using the method according to claim 16, and a manufacturingstep, in which the pair of spectacle lenses is manufactured.
 18. Amethod for optimizing at least a lens of a pair of spectacle lenses byoptimizing the value of at least one binocular criterion determinedaccording to claim 13, wherein the method comprises: a lenses providingstep, in which a pair of spectacle lenses is provided, an analyzingstep, in which the binocular performance of the pair of spectacle lensesis analyzed according to the method according to claim 13, a modifyingstep, in which at least one of the two lens is modified, wherein theanalyzing and modifying steps are implemented by technical means andrepeated so as to optimize the binocular performance of the pair ofspectacle lenses.
 19. A computer program product comprising one or morestored sequence of instruction that is accessible to a processor andwhich, when executed by the processor, causes the processor to carry outthe step of claim
 18. 20. A computer readable medium carrying one ormore sequences of instructions of the computer program product of claim19.